Many applications require an antenna which can transmit/receive two orthogonal polarizations. A common technique to achieve either this, is the addition of ridges to the horn antenna. Machining costs are expensive due to the high precision needed in the antenna. The 4 waveguide-fed pyramidal horn achieves this specification and is relatively inexpensive to manufacture.
The structure consists of four individual rectangular waveguide sections which are connected and separated by a central metallic block which extends the length of the waveguide. Each waveguide is flared in both directions to create an aperture which forms a cross. The waveguides are excited in parallel pairs (ports 1&3 or ports 2 & 4).
Due to the in phase excitation of the two waveguides in the dominant mode and the cross shaped design of the flare, a more symmetrical aperture field distribution in the central ‘square’ of the aperture may be achieved. This results in a symmetrical radiation pattern with good cross polarization characteristics....
The reflection bandwidth is limited by the frequency range of the waveguide section. Good cross polarization is achieved over this bandwidth, with beam symmetry limited to a region centered around the design frequency.Typical radiation pattern at the center frequency; Typical normalized radiation patterns at the center frequency.